# coding=utf-8
__author__ = 'huhai'

class C():
    @staticmethod
    def c_a():
        return 'aa'
        
    @staticmethod
    def c_b():
        return 'bb'
        
    @staticmethod
    def c_c():
        return 'cc'
        
def output(format=None):
    output_func = getattr(C, "c_%s" % format, C.c_c)
    return output_func()
    
if __name__ == '__main__':
    print output('a')
    print output('b')
    print output()
    